Restructuring and Other Charges, Net - Schedule of Restructuring and Other Charges, Net by Reportable Segments, Pretax (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	$ 149	$ 125
Operating Segments
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	147	126
Corporate [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	2	(1)
Alumina [Member] | Operating Segments
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	1	58
Aluminum Segment [Member] | Operating Segments
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	$ 146	$ 68